The invention relates to the use of beam interrupters in photographic and other optical equipment, such as copying devices and the like.
More particularly, the invention relates to beam interrupters of the type, for example, wherein use is made of shutter blades or color filter paddles which are moved by electromagnetic means about a pivot axis oriented generally parallel to the direction of the light beam, into and out of the path of the light beam.
Light interrupters are already known in which there are mounted on a plate a plurality of rotary electromagnet devices arranged adjacent to an opening for the light beam. Each of the rotary electromagnet devices is operative for moving a respective one of a plurality of light interrupting components, for example filters, into the path of the light beam. Such rotary electromagnet devices, when used to so move light-interrupting components, are disadvantageous; they have a relatively large mass which must be accelerated, and they give rise to relatively great frictional energy losses resulting from the conversion of linear motion into rotary motion by means of a crank device. Such motion-imparting devices are accordingly not well suited for light interrupters, when the light-interrupting components must be moved with a very high speed into the path of the light beam of, for example, a copying device.
Modern color copying devices employ copying times for individual negatives on the order of magnitude of a few tenths of a second. The time available for introducing a filter into the path of the light beam of the copying device is on the order of a few hundreths of a second. The aforementioned rotary electromagnet devices are not suitable for use in the light interrupter of such a copying device. In addition, they do not permit a controlled return motion of the light-interrupting components.